1.Field of the Invention
The present invention relates to a brake oil-pressure control valve device, in vehicles particularly four wheel automobiles where hydraulic circuits for front and rear wheel brakes are formed into two systems independently of each other, wherein the operating oil pressure of the rear wheel brake is automatically controlled in accordance with the braking force as required.
2. Description of the Prior Art
In the past, the control valve devices of this kind include one device wherein in an oil passage for connecting an output port of a master cylinder to the rear wheel brake there is provided a reducing valve capable of proportionally reducing output oil pressure of the master cylinder to transmit the pressure to the rear wheel brake, and the other wherein in the oil passage there is provided a weight valve which cuts off the oil passage as it senses a reduced speed more than a preset value of the vehicle. However, in the case of the former, since a folding point in the braking force distribution curve is constant, the device is not suitable for use in vehicles such as trucks which vary in vehicle weight depending on the loaded or unloaded condition and extremely vary in load distribution of the front and rear wheels. Also in the case of the latter, there is a problem that the device may not sufficiently respond to the change in load weight.